I like that idea, and I don't think a multiple downvote system would have to be hard to implement. It would take very little change to the site, for example, to

I like that idea, and I don't think a multiple downvote system would have to be hard to implement. It would take very little change to the site, for example, to promote a system in which we flag for spam, downvote for irrelevance, and reply to posts we perceive as factually incorrect.